Cleaner shrimps form mutualisms with fish for the removal of ectoparasites,
however have been far less studied than cleaner fish. Unlike cleaner fish,
cleaner shrimps range in colour and behavioural signals among species. They
have also been observed to form associations with anemones and corals, with
such a multi-level symbiotic system further complicating attempts to understand
their relationships with fish. Huebner and Chadwick (2012) aimed to investigate
the visual role of the sea anemone Bartholomea
annulata and the shrimp Ancylomenes
pedersoni on the cleaning interactions formed with fish and how the fish
responded to manipulation of these factors.
The study was conducted at two coral reef sites located at
Brewers Bay and Flat Cay, located next to the Virgin Islands in America. Divers
collected visual observations across 77 fish cleaning stations from 6:30 – 8:30
over a week during March, July and November 2009 and February 2010. They
recorded the number of fish visits in addition to the visual features of the
anemones including body size, height of tentacles, distance tentacles extended
beyond the surrounding substratum, the number of shrimps and the total number
of symbiotic crustaceans. Some cleaning stations were manipulated with a brown
coloured mesh covering anemones and shrimps to analyse their visual effects on cleaning
interactions, including both covered, only one covered and a control of none
covered.
They found increased fish visits to anemones with a larger
body size and total symbiotic crustaceans, although these two variables were
not related, however when the covers were added there was an inconsistent
response. Fish only posed for cleaning when the anemones were visible,
regardless of shrimp visibility, meaning a decreased number of cleaning
interactions were recorded when the anemones were covered. This suggests the
anemones act as beneficial symbionts to the shrimps as they are a visual cue
for the cleaning of fish. Fish were also observed repeatedly searching around
the anemones that had been covered, suggesting they may act as a landmark that
represent cleaning opportunities for fish. This was further indicated as fish
posed at visible anemones even when the shrimps were covered, despite being
close enough to be able to visually detect no shrimps were available. This may
be related to the fact shrimps are sometimes hidden in crevices around the
anemones, therefore the act of posing by the fish may cause the shrimps to
emerge, further suggesting the anemones play an important role in the symbiosis
of cleaning interactions. Nonetheless further research is required to determine
the specific visual cues the anemones provide to these symbionts and the
benefits obtained by each member in this complex system.
Huebner, L.K. and Chadwick, N.E. (2012). Reef fishes use sea
anemones as visual cues for cleaning interactions with shrimp. Journal of Experimental Marine Biology and
Ecology. 416, 237-242.
Hi Aimee,
ReplyDeleteThis is very interesting! I just have a few questions though:
Is the anemone giving off purely a visual stimulus or is there any release of a chemical attractant by the anemone? Maybe an extracellular protein which the fish can 'smell'?
Does the anemone give any direct benefit to the shrimp other than the attraction of fish? (again, maybe an extracellular protein or something?)
Did the authors make any controls for the potential habitation of the anemone by the ectoparasites? How do they know for sure the fish is the source of the ectoparasite?
Thanks, Harri
Hey Harri,
ReplyDeleteThere was no mention of the anemone producing any chemical stimulus that attracted the fish, but they did not test for this as they were just analysing the visual stimulus it provided. So I guess that could be another factor that would be interesting to investigate!
The shrimps have been observed to hide in and around the anemones, which may provide them with protection from predation, then when a fish poses on the anemone the shrimps emerge and begin to clean. The paper just mentioned that the shrimps form obligate associations with the anemones but didn't state the reasons why. I'm not sure that they fully understand the benefits they provide yet, but there's another paper that discusses the selection of anemones by the species Ancylomenes pedersoni if you wanted to have a look, here's the link: http://www.sciencedirect.com/science/article/pii/S0022098111005259
Again ectoparasites on the anemones wasn't something they tested for, but it seems the shrimps wouldn't have much need for the fish if this was the case, so I assume they are only found on the fish.
I hope this answers your questions!
Aimee
This is an interesting paper, however it doesn't really show anything... If the data (in the linked paper. Mascaro et al, 2012) shows the shrimp do not significantly choose to hang out near the coral then how can this paper (Huebner & Chadwick, 2012) say that the shrimp actively do this??
ReplyDeleteDo the authors make any mention of free-living (i.e. non-mutalistic) shrimp which do the same job and clean fish but not near a coral?
That's a good point!
ReplyDeleteWell Huebner and Chadwick state that there is a great variation in the behaviour signals displayed between species of cleaner shrimps and that some species have displayed associations with anemones. Those that do have been observed to base their cleaning stations around the anemone and will only interact with the fish if it comes within a specific distance of the anemone.
Although Mascaro et al. didn't find any preference of Ancylomenes pedersoni on specific anemones, this was an ex-situ experiment and therefore may not give a true representation of the associations that would form in the natural habitat of these species. Also, they claim that differences in the associations formed by the shrimp may be related to the presence of a range of possible anemone hosts they must decide between, however Huebner and Chadwick did not mention the presence of other anemone species so it's difficult to determine whether this would have effected this specific study.
Also, since Mascaro et al. did not include fish in their study, it could be proposed that the presence of the fish may result in a response by the anemone, such as a release of chemicals, that attracts the shrimps. However this is obviously a complex system of symbionts and there are so many different factors that could be of influence, so it definitely sounds like an interesting aspect for further study!
Fascinating study .... but are there any microbial connections?
ReplyDeleteOh dear, no the study doesn't really analyse any specific microbial aspects. I read this paper and was so interested in the mechanisms of a multi-system symbiosis that I guess I may have temporarily forgotten we are meant to be focusing on microbes, I'm sorry!
ReplyDelete